1. Animal studies have shown that prostaglandins are important for renal function after unilateral nephrectomy. In order to investigate the importance of prostaglandins for renal function in the fully adapted remnant kidney in healthy uninephrectomized subjects, the acute effects of indomethacin on renal haemodynamics, lithium clearance, urinary excretion rates of prostaglandin E2, sodium and water, and plasma levels of angiotensin II, aldosterone, atrial natriuretic peptide and arginine vasopressin were measured in 14 healthy uninephrectomized subjects (median time after nephrectomy 1.7 years) and in 14 matched healthy control subjects. In addition, nine healthy control subjects were studied without indomethacin and served as a time-control group.
2. Before indomethacin ingestion there was a significantly higher single-kidney urinary excretion rate of prostaglandin E2 in the uninephrectomized group (uninephrectomized group, 349.2 fmol/min; control group, 76.6 fmol/min; time-control group, 96.3 fmol/min).
3. Indomethacin ingestion resulted in equal changes in all parameters in both groups. These were significant decreases in glomerular filtration rate (−11.3% versus −14.6%), renal plasma flow (−6.5% versus −13.0%), urinary flow rate (−49.8% versus −49.4%), fractional sodium excretion (−44.5% versus −47.4%), lithium clearance (−33.2% versus −23.8%) and urinary excretion rate of prostaglandin E2 (−93.8% versus −86.7%) (uninephrectomized versus control subjects, values are medians). In the time-control group no changes were observed in these parameters.
4. It is concluded that healthy uninephrectomized subjects with a fully adapted remnant kidney have a normal renal response to acute indomethacin-induced inhibition of prostaglandin synthesis.